Nonlinear fracture analysis of single-layer graphene sheets

In this paper, an atomistic based finite element model for prediction of fracture behavior of single-layer graphene sheets is developed by considering large deformation and nonlinear geometric effects. Euler-Bernoulli beam elements are used to represent covalent bonds and non-linear characteristic of the beam elements are obtained by using the modified Morse potential. Formulation underlying the proposed approach is applied to defect-free, and Stone-Wales and one atom vacancy defected zigzag and armchair graphene sheets. It is shown that large deformation and nonlinear geometric effects are important on the fracture behavior of graphene sheets. The results show that graphene sheets exhibits an orthotropic fracture behavior and these defects significantly affect the mechanical performance of the graphene sheets. In addition, fracture initiation and crack propagation direction issues are studied. It is observed that the fractures of all types of graphene sheets are brittle.